<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>定位</title>
</head>
<style>
    .div01{
        height: 200px;
        width: 200px;
        border: 1px solid red;
        background-color: blue;
        /*float: left;*/
        position: absolute;
        /*position: relative;!*没有脱离标准流，独占一行*!*/
        z-index: -2;
    }
    .div02{
        height: 200px;
        width: 200px;
        border: 1px solid red;
        background-color: greenyellow;
        /*position: relative;*/
/*position: relative;*/
/*        float: left;*/
        z-index: 5;
    }
</style>
<body>
<div class="div01"></div>
<div class="div02"></div>
</body>
</html>